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Monthly Archives: September 2012

Whilst in Madrid, my geeky interest in engineering combined with my self-preservation interest in not melting in the 30+ degree heat, drawing me to the Madrid Rio Project.

Back in the 70s, the M30 motorway was built right through Madrid. It followed the route of the Manzanares river, cutting off the two halves of the city from each other and leaving the river in a narrow, inaccessible channel between the carriageways. OK, you might think, that’s the sort of thing urban planners liked to do in the 60s and 70s. (You should see what they nearly did to Edinburgh! Motorways ploughing through the Meadows and crossing the east end of Princes Street on stilts. I’m not making this up). They’d never get away with it now, but the damage is already done… people might not like having six lanes of heavy traffic hammering along what could have been the city’s waterfront, but it’s there now and getting them to accept the traffic chaos that would be caused by getting rid of it would be a pretty hard sell.

Puente de Toledo crosses the new park

However, get rid of it they have. In a mammoth infrastructure project from about 2005-2008, the M30 was buried in Europe’s longest urban motorway tunnels, and the surface transformed into a 6km long linear park along the restored banks of the river. Although the cost was massive (I saw $3.9 billion just for the tunnels from one source and I can well believe it), the result has been a huge reduction in noise and pollution, improvements in road capacity and safety, and perhaps most importantly the replacement of a road that was a serious barrier and a blot on the landscape with open, welcoming green space, helping to join the city back together again.

New fountains at the Puente de Segovia

I heard about the project shortly before I went to Madrid and knew I had to go and see it. I have to say, it exceeded my expectations. The scale of the thing is amazing, there are all sorts of facilities from paths to open air bars to children’s play areas, and the whole area felt exceptionally clean and safe. Apart from a few air vents and some slip roads popping out of the ground in odd places, little evidence of the subterranean motorway is visible.

A sliproad disappearing into the ground gives a clue as to where the M30 has gone.

For hot days, though, the “City Beach” is a work of genious. There are shallow water pools with lovely, cooling fountains so when the temperatures start to get too much, you can go stand in the spray until you cool off again. It certainly made the afternoon sunshine a lot more bearable for a pale northerner such as myself.

So… why can’t they put the M8 through Glasgow underground and build a beach on top? (OK, don’t answer that 😉 ).

Puente de Segovia by night

Update: I’m in Madrid again now (1/12/2012), and this time it’s cool enough to actually walk the whole length of the Rio Project, so I did. Well, actually I don’t think I quite made it to the southern end – it wasn’t obvious where to go so it looks as if either they haven’t completed the whole thing as shown on the maps, or I was just being dumb and not noticing the continuation.

I’d already seen probably the most impressive bits, the parks centred on the two old bridges, but walking the whole thing does give a better idea of the sheer scale of it. The whole distance was nicely landscaped and seems to be quite heavily used even in the cooler weather. I also discovered that they haven’t completely buried the motorway – a section of the northbound carriageway is still on the surface where it passes the stadium, giving a good idea of what the whole thing must have been like before, and why they would’ve wanted to change it.

I’ve been enjoying playing with the Raspberry Pi again lately. One of the Pi’s more unusual features is that it comes as a bare circuit board with no case, both to keep the price down at the $35 mark, and so that people can choose (or build) their own cases. So far, my Pi board has mostly just been lying on the carpet under my desk, in amongst the tangle of cables going to and from my main computer, TV, music keyboard and various peripherals. It seems happy enough down there, but there’s always a slight worry in the back of my mind that it’s going to get trodden on (it’s already endured one of Laura’s folders falling on it), zapped by static electricity, or that I’m going to damage something when I hold it to unplug one of the cables.

The case arrived quickly, in a padded envelope for protection. The Pi slots into it nice and easily and fits snugly once it’s closed. The lid is easy to prise open, but all the Pi’s main ports and the SD card slot are easily accessible through the pre-cut holes in the sides so I probably won’t need to open it very often. The case is all plastic so it removes the danger of anything getting static zapped, or metal accidentally touching the board and causing a short circuit. Inserting and removing the tighter fitting connectors (especially the micro USB power plug) feels a lot safer now that I can grip onto the box rather than risking crushing a capacitor or stabbing myself on the GPIO pins.

In addition to the holes for the ports, there are various ventilation holes (although the Pi generates very little heat compared to most electronic devices). And there’s these:

A common complaint about the original Raspberry Pi board design was that it had no mounting holes, making it difficult to securely attach the Pi to something, which you may want to do if you’re building it into a larger project, or even just to stop it being pulled all over the place by its cables. The ModMyPi case remedies this by including its own mounting holes, making it easy to screw the Pi onto whatever you please. (The new Revision 2 Pi boards do have mounting holes, but there are a lot of revision 1 boards like mine already out there so it’s a useful feature in a case). But if you just want to sit the case on a desk, there are four little sticky rubber feet supplied that help stop it from sliding about and keep the bottom air vent open.

One possible downside is that the case makes it harder to get at the GPIO pins and to see the status LEDs. However, this is unlikely to be a huge problem in practise; the GPIO pins are mainly only useful to people who want to interface their Pi to custom electronics, something probably only a minority of users will ever do (I haven’t tried it yet myself, but would like to when I get the time). Even then, it would be easy enough to run wires to the GPIOs through one of the pre-cut openings in the case. As for the LEDs, they’re only really useful for troubleshooting when something goes wrong, which hopefully is rare enough that having to pop the case open won’t get annoying. There are slots right above the LEDs, so you can still see at a glance whether the Pi is powered up or not, which is the only thing I normally use them for.

The box seems quite well designed and built. There are no obvious weak bits that look likely to break off, and it still closes nice and firmly even after me fiddling with it quite a lot.

It also goes quite nicely with the external battery pack I’ve been using:

So if you’re looking for a Pi case, this seems like a very good option :).

I’ve had a few emails and comments over the past months about my Raspberry Pi emulators… mostly noting that they won’t compile on the new Raspbian OS that was released for the Pi last month. Finally, after being busy travelling the world and working on other projects for a while, I had some time to look into this :).

(Well actually, I did look into it a couple of weeks ago. I fixed the compilation issue in a few minutes as it was mostly just a case of libraries moving to slightly different locations… but then when I tested Tetris on the Gameboy one, it stubbornly failed to run, just freezing up on a white screen. I could play Mario and Sonic fine, none of the other games had problems. Only Tetris. I couldn’t understand how on earth such a subtle change to the build process could have broken one game and left all the others unaffected, so I suspected this was going to be a long drawn out and annoying thing to debug and put it aside for a while. Today I had psyched myself up ready to dive in, but before I started I had a thought: what if my Tetris ROM file got corrupted when I copied it to my shiny new Raspbian SD card? Not very likely, but worth ruling out anyway. Bingo! After copying the ROM again, it worked fine. No subtle bug after all. I could have released this update weeks ago. Sorry).

So… updated versions that should build on Raspbian are now up on the emulators page. The Raspbian-compatible Makefile is now the default one, but the old one is still there as Makefile.squeeze just in case anyone wants it. You may also need to change to the ilclient directory (/opt/vc/src/hello_pi/libs/ilclient) and run “make” in there to build it before you can build the emulators for the first time, as it’s distributed as source code.

Nothing much else has changed… I tested my Pi with composite video instead of HDMI and discovered that running the emulators with HDMI audio when HDMI’s not in use crashes them. So HDMI is no longer the default, the analogue port is the default and you need to pass ‘-h’ on the command line to use HDMI.

Enjoy :). I have something else in the pipeline that I’m hoping won’t take as long to materialise as this update did.

"I think who [gcat] is, really, is a very caring and non-judgemental person... and a bit of a nerd. And for me, that word has no negative connotations whatsoever. He's not one of those trendy new nerds who are basically normal people who like superhero movies. He's a proper, old-school nerd who gets absolutely obsessed with the most obscure subjects, regardless of whether anyone else is into them or not".